For the purposes of ablation, a catheter with a unipolar electrode, a so-called endocardial catheter, is introduced into the heart. A large-surface electrode is placed on the patient's skin as a counter-electrode. If the electrodes are supplied with suitably shaped voltage, energy is applied to the cardiac muscle.
The disadvantage of this is that the target is not always hit accurately and instead surrounding tissue can be damaged by the electrical energy.
It is known from cardiosurgery to use forceps-like devices for ablation with two cheeks with one of these cheeks being introduced through a hole in the atrial wall of the heart. The cardiac wall is then clamped between the cheeks before a defined energy is fed through the cheeks.
This method from cardiosurgery is precise, but requires the thorax of the patient to be opened up.